Like any other agricultural crop, pesticides are applied to hemp plants to protect it from pests and improve growth yield. Chronic exposure to pesticides can lead to serious health risks and therefore pesticide analysis in hemp products is important for consumer safety and quality control. Among all of states in USA, California has issued most stringent action limits for 66 pesticides residues in cannabis  matrices.  Colorado has issued even more stringent regulatory limits than California state for 102  pesticides residues in hemp products.  Normally pesticide analysis in hemp and other food matrices is done by both GC/MS/MS and LC/MS/MS since some nonpolar and chlorinated pesticides such as pentachloronitrobenzene, etridiazole, fenvalerate, iprodione, chlorfenapyr and others are difficult to ionize with electrospray source used in LC/MS/MS systems.   We would demonstrate how we measured these compounds at low levels using LC/MS/MS with APCI source. The ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene and others using LCMSMS system with APCI source would be presented. Hemp matrix is challenging and therefore it causes ion suppression and matrix inference for response of some of pesticides. We would demonstrate approaches to mitigate these ion suppression and matrix effects from hemp matrix to achieve method accuracy in range of 80-120 %. Sample preparation is the main bottleneck for achieving the high throughput analysis of pesticides in cannabis and hemp testing labs. For sample preparation, we used automated solvent extraction since it is more quicker, cheaper, greener and easier way to achieve high extraction recovery for pesticides in comparison to other time-consuming, difficult and expensive sample preparation techniques like solid phase extraction (SPE) and QuEChERS with dSPE( dispersive solid phase extraction) which show poor extraction efficiency.

Overcoming challenges associated with analysis of pesticides regulated by Colorado state in hemp using a novel LC/MS/MS method with dual ESI and APCI source

ACS Spring 2022

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